Optimal Strategy with a Nonzero-Sum Game

 Here is my feedback I got back, but I still don't understand. Please help!

Q1) You will need to relook at this one.  I STILL disagree.  Also, you need to systematically check for dominant strategies as well as for Nash Equilibriums. 

Q3) The equations you have here are not correct.

Q5) Can you recreate the error made by coworker?  It is a common one.